Answer:
Either pressure from their partner or forgetting to take pills/proper protection
Step-by-step explanation:
It's quite common from teens to expierence pressure into sexual acts and they seem to trust their partner more when they say they don't need protection at all, and yep even if you take birth control you might forget it ,, so it is the reality since 9 out of 100 pill users forget and end up getting pregnant ,, hope this helps !